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7 th ICOS Meeting Berlin 04.07.2013

7 th ICOS Meeting Berlin 04.07.2013. Presentation by Jennifer Slobodda. Short repetition of the last presentation Comparisons to MODIS Cloud Tracking and Cloud Livecycle Representativity study. Retrieval for effective Radius and optical depth from SEVIRI

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7 th ICOS Meeting Berlin 04.07.2013

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  1. 7th ICOS MeetingBerlin 04.07.2013 Presentation by Jennifer Slobodda Cloud Seminar Jennifer Slobodda

  2. Short repetition of the last presentation • Comparisons to MODIS • Cloud Tracking and Cloud Livecycle • Representativity study Cloud Seminar Jennifer Slobodda

  3. Retrieval for effective Radius and optical depth from SEVIRI • Combination of 0.6µm, (0.8µm), 1.6µm (and 3.9µm) to retrieve cloud optical depth (COD), effective radius (Reff) (and cloud top height (CTH)) • Separation of radiative effects of clouds, atmosphere and ground (DCOPM; Walther and Heidinger 2012) Atmospheric correction above cloud Cloud properties above black surface Albedo + atmosphere below cloud Cloud Seminar Jennifer Slobodda

  4. In formulas Only for thermal channels Atmospheric correction above cloud TOC – top of cloud cld – cloud abc – atmosphere below cloud aac – atmosphere above cloud Mes – measured RSc – Rayleigh scattering R – reflectance T – transmission S – spherical albedo A – surface albedo I – radiance F0 – solar irradiance µ0 – cos(solar zenith) d – earth-sun distance B – planck function ε - emissivity Cloud Seminar Jennifer Slobodda

  5. KNMI correction of SEVIRI calibration: • Recalibration of SEVIRI data with MODIS measurements • Channel 1 (640nm) : correction factor ~1.08 • Channel 2 (805nm): no correction • Channel 3 (1635nm): correction factor ~0.97 • Channel 4 (3900nm): no correction Cloud Seminar Jennifer Slobodda

  6. Comparison COD SEVIRI (FUB) and MODIS (official) Cloud Seminar Jennifer Slobodda

  7. Comparison Reff SEVIRI (FUB) and MODIS (official) Cloud Seminar Jennifer Slobodda

  8. Time Series of histograms including MODIS (COD) Cloud Seminar Jennifer Slobodda

  9. Time Series of histograms including MODIS (Reff) Cloud Seminar Jennifer Slobodda

  10. Comparison to ground-based measurements • calculating water content with retrieved values of optical depth and effective radius for the Pixel next to Juelich/Leipzig including paralax shift • calculation according to different papers • Fu 1996 : • Ebert 1992: • Wang 2002: • Wasser : Cloud Seminar Jennifer Slobodda

  11. Comparison to ground-based measurements of the IWP from Jülich Cloud Seminar Jennifer Slobodda

  12. Comparison to ground-based measurements of the IWP from Jülich (27.07.12) Cloud Seminar Jennifer Slobodda

  13. Comparison to ground-based measurements of the CWP from Leipzig (06.07.12) Cloud Seminar Jennifer Slobodda

  14. Comparison to ground-based measurements of the CWP from Leipzig (05.07.12) Cloud Seminar Jennifer Slobodda

  15. Cloud Tracking • program written by Marc Schröder • based on cloud overlap in two time steps • identification of convective cells with 10.8µm-BT threshold (default is 230K ) • mainly calculates mean values of BT or radiance/reflectance, lon & lat, number of pixels… • I want to modify the code so that I can calculate mean values of microphysical cloud properties Cloud Seminar Jennifer Slobodda

  16. Cloud Tracking – Beispiel 23.05.2012 Cloud Seminar Jennifer Slobodda

  17. Cloud Tracking and Lifecycle • Examination of time-series of convective cells • Identification of the cell at the next time step (criteria) • how do mean values of COD and Reff change REff ? t COD Cloud Seminar Jennifer Slobodda

  18. Representativity • all data from SEVIRI channels 0.6µm, 0.8µm, 1.6µm and 10.8µm over one year for 21x21 Pixel • deviding according to fully cloudy, clear and partly cloudy • calculating correlation between the time series of each Pixel to the Pixel in the middle • calculating mean values and standard deviations for each pixel Cloud Seminar Jennifer Slobodda

  19. Represtativity - correlation in Juelich for clear sky Cloud Seminar Jennifer Slobodda

  20. Represtativity - correlation in Juelich for cloudy sky Cloud Seminar Jennifer Slobodda

  21. Represtativity - correlation in Juelich for partly cloudy sky Cloud Seminar Jennifer Slobodda

  22. Represtativity - correlation in Leipzig for cloudy sky Cloud Seminar Jennifer Slobodda

  23. Represtativity - correlation Zugspitze for cloudy sky Cloud Seminar Jennifer Slobodda

  24. Represtativity - correlation for COD and Reff Zugspitze for cloudy sky Cloud Seminar Jennifer Slobodda

  25. Represtativity for case study Cloud Seminar Jennifer Slobodda

  26. Represtativity for case study Cloud Seminar Jennifer Slobodda

  27. Summary and Outlook • with recalibration quite good agreement between my MSG retrieval and MODIS • increasing of optical depth and effective radius during a cloud lifecycle • though the methods to calculate IWP from Reff and COD weren’t developed for thunderstorms initially the values agrees quite well with ground measurements • for cloudy sky the representativity of the ground measurement decreases after about 3x3 MSG-Pixel (10-15km) especially for complex ground below the clouds; for optical propertie the correlation is even worth • cloud tracking provides first results but has to be modified for the intended usage Cloud Seminar Jennifer Slobodda

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